A procedural macro which creates a "staged" builder for a type.

Staged (also known as telescopic) builders are a style of infallible builders; code will not compile if any required fields are not set. Specifically, the builder advances in order through a sequence of "stage" types, each corresponding to a required field of the struct. The final stage has setters for all optional fields and the final .build() method.

See the documentation for #[staged_builder] for more details.

Examples

use staged_builder::staged_builder;

#[staged_builder]
struct Person {
    #[builder(into)]
    name: String,
    age: u32,
    #[builder(list(item(type = Person)))]
    parents: Vec<Person>,
}

let person = Person::builder()
    .name("John Doe")
    .age(25)
    .build();